Automatic switch mechanism



AUTOMATIC SWITCH MEGHANI SM Filed Jan. 18. 1926 Fig.1.

ATTORNEY Patented Mar. 20, 1928.

UNITED STATES 1,663,325 PATENT OFFICE.

CARL H. WOLFE, OF ST. LOUIS, MISSOURI, ASSIGNOR TO WAGNER ELECTRIC CORPORA- TION, OF ST. LOUIS, MISSOURI, A CORPORATION OF DELAWARE.

AUTOMATIC SWITCH. MECHANISM.

Application filed January 18,1926. Serial No. 82,056.

My invention relates to eentrifugally operated switch mechanism, a specific application being for the purpose of opening the circuit of the split phase Winding of a single phase motor when a suitable speed has been attained.

Among the objects of my invention is to provide a device in which while the circuit closing member is mounted on the rotor and the contacts with which it cooperates on a stationary part of the machine, the former will be stationary when in circuit closing position, thus avoiding frictional wear and sparking at the contacts.

Other objects and advantages of the invention will appear from the following description. v In the accompanying drawings Figure 1 is a side view of the switching apparatus embodying my invention, this figure also showing a suflicient portion of the stationary and rotating parts of the motor to show its application thereto; Figure 2 is a view partly in section and part1 in elevation of the portion of the switc iing mechanism mounted on the rotor, said view being taken on the line 22 of Figure 1; Figure 3 is a front view of the centrifugal members and associated parts; and Figure 4 is a rear view of the stationary contacts and their mountin s.

lhe stator of the machine is provided with a main field winding and a split phase starting winding, the end turns of said windings being'diagrammatically indicated at 1. The split phase starting winding is connected to the spring contact members 2 which are mounted on the end plate 3 of the machine, being insulated therefrom by block 4, and the free ends of these members 2, which carry the contac ,..are positioned on opposite sides of the haft of the rotor 5.

A collar 6 is slidingly and rotatively mounted on the rotor shaft and is provided with peripheral grooves at each end. An annular disk 7 of insulating material is carried in the forward groove, said disk being rotatable with respect to the collar 6 and fitting somewhat loosely in the groove in said collar to permit slight tilting of the disk from a plane at right angles to the rotor shaft. An annular conducting ring '8 is secured to the insulating disk 7 and, under conditions hereinafter described, serves to electrically connect the contact members 2- and therefore close the circuit of the split phase winding.

Weight members 9 are pivotally mounted at one end in frame 10, which is secured to the rotor to rotate therewith. Springs 11, whose ends are connected as shown to the angular portions of the weights adjacent to the pivots, serve to normally hold? the weights in the position shown in Figure 1. The weights are provided with extensions 12 which carry pins 13 engaging with the groove in the rear end of the collar 6.

The forward motion of the contact members 2 carried by the stator frame is limited by adjustable screws 14 which are provided.

with headed stops of insulating material 15 extending through the openings 16 in the contact members 2.

Referring to the operation of the mechanism described, Figure 1 shows the normal position of the parts with the rotor stationary, in which position the circuit of the split phase winding is closed. The governor weights 9 are so shaped and proportioned that the moment of inertia about their pivot points increases rapidly with speed and therefore as the speed rises the free ends of the weights move to the right (as viewed in Figure 1) against the resistance of the springs 11, and through their connection with the collar 6 move the circuit closing ring 8 out of engagement with the contacts carried by the members 2. During the initial portion of this motion the contacts follow the ring 8 and the circuit is therefore maintained until a desired percentage of full load speed has been reached, at which time the forward motion of the contact members is arrested by the stop members 15, and the circuit of the split phase winding is opened with a quick sparking.

In stand still position the action of the springs 11 not only maintains pressure between the contacts and the ring 8 but also holds the insulating disk 7 against the ends of the stop members 15. The friction at the break which avoids points named is at this time greater than the between the contacts and the ring 8 is su-fii- The slight tilting of the disk 7 previously referred to aids in securing positive contact between the contact points of the ringc8 under all conditions, and the adjustability of the stop members 14 permits adjusting the point of opening of the circuit of the split phase winding with respect to the speed of the motor after the particular motor has been completely assembled. Thus variations in operating characteristics of particular short cireuiting mechanism, due to variations in manufacture, can be readily compensated for without expense and the motor given the desired operating characteristics with respect to the time of opening the circuit of the split phase winding.

Having fully described my invention, what I claim as ne and desire to secure by Letters Patent of the United States is:

1. In a dynamo electric machine having stationary and revolving parts, a pair, of resiliently mounted contacts carried by a stationary part, stop members limiting theforward movement of said contacts, a circunoeaaae lar circuit closing member mounted on a revolving part of the machine, means holding said circuit closing member in engagement with said contacts and in frictional engagement with said stops when the revolving member is at rest, and centrifugal means for moving said circuit closing member out of engagement with said contacts and stops when the revolving member has attained a predetermined speed.

2. In a dynamo electric machine having stationary and revolving parts, a pair of resiliently mounted contacts carried by a stationary part, stop members limiting the forward movement of said contacts, an annular circuit closing member slidingly and rotatively mounted on a revolving part of the machine, said annular member being mounted on a disk of insulating material, and means holding the annular member in engagement with the contacts and the disk in frictional contact with the stop-members when the revolving member of the machine is at rest, said means-comprising centrifugal means for moving said annular member out of engagement with said contacts and stops when the revolving member has attained a predetermined speed.

in testimony whereof, I hereunto afiix my signature, this 12th day of January, 1926.

(CARL) C. H. WOLFE. 

